Since May of 2006, we have observed neural tube defects (NTDs) in untreated control mice. NTDs are serious birth defects affecting 320,000 children annually resulting in severe disability or death. Most NTDs result from environmental factors altering the development of a genetically susceptible fetus. As such, they can be prevented, for example, folic acid fortification of grains reduced NTDs by 1/3, saving $400 million annually. The cause of the unknown NTDs in mice was localized to municipal tap water. Providing distilled deionized water eliminated NTDs. The malformations reappeared when mice were placed back on tap water from Blacksburg, VA, Washington DC, or Baltimore, MD in a dose dependent manner. The problem appears to be widespread since commercially purchased pregnant mice (shipped after the time of NT closure) from suppliers located in Lansing, MI, Raleigh, NC, Dublin, VA, and Germantown, NY all arrived with NTDs. One feature common to water from these widely varying regions is the water treatment method. Concerns regarding the safety of disinfection by-products (DBPs) recently led the EPA to revise guidelines regulating DBPs. Many utilities began treating with chloramine to meet the new guidelines. Concentrations of known and regulated DBPs have declined, but new DBPs have inadvertently been produced. The goal of this project is to determine the cause of the NTDs in control mice. This project utilizes an established multidisciplinary research team to test the hypothesis that DBPs in tap water are responsible for observed NTDs, and that the teratogen now present in the water resulted from a switch to chloramine treatment. Specific aims to test this hypothesis are to unequivocally establish whether DBPs are responsible for the NTDs in mice and other species, and to systematically characterize and identify the compound or class of compounds in tap water responsible for NTD formation. The results of this study will help determine if there is an increased risk to human health and development. PUBLIC HEALTH RELEVANCE: This study will determine if the malformations observed in mice and Drosophila are caused by ambient disinfection by-products (DBP) present in tap water and also determine if tap water is teratogenic to rats. This study may indicate an increased health risk to humans and is the first step to regulate concentrations of new DBPs. This project will improve local economic conditions directly by employing 2 PhD students, providing significant salary support for a technician and PI and indirectly supporting many other positions within the university infrastructure.